Interspecies sensitivity in the aquatic toxicity of aromatic amines

It is known that Daphnia magna is highly sensitive to aniline. The objective of this study is twofold: (i) to find out if also other aromatic amines are more toxic to Daphnia; and (ii) to investigate if also other species are more sensitive to the effects of aromatic amines. Sensitivity histograms of anilines have been constructed based on literature data, taken from several publications, for acute toxicity to several species. The sensitivity distributions show that in particular water fleas are highly sensitive to some of the aromatic amines. Data for the acute and chronic excess toxicity of anilines and other ‘polar narcotics’ for D. magna has been analyzed. Anilines are significantly more toxic than other polar narcotic compounds. In addition, the acute to chronic ratios in D. magna are also higher for anilines than for other ‘polar narcotics’. Finally, the effects of the position of the substituents on the excess toxicity to D. magna have been examined. Results show that excess toxicity is lower in case of ortho substituted aromatic amines. This may indicate a steric hindrance of the ortho substituent in the toxic process of anilines to daphnids.